html,body{
    width:100%;
}
.content{
    width:75%;
    margin:0 auto;
}
.mainpic{
    width:49%;
    box-sizing: border-box;
}
.mainpic img{
    width:100%;
}
.xiangqing{
    width:49%;
}
.xiangqing img{
    width:100%;
}
.xiangqing img{
    margin:5px 0;
}
.section1,.section2,.section3,.section4,.section5,.section6,.section7,.section8{
    margin:80px 0;
}

.item img{
    width:100%;
}
.imgs{
    transition: all 0.5s;
}

@keyframes changes {
     from{
         opacity: 0;
     }
     to{
         opacity: 1;
     }
 }

@keyframes changed {
    from{
        opacity: 1;
    }
    to{
        opacity: 0;
    }
}
.changes{
    animation: changes 0.5s forwards;
}
.changed{
    animation: changed 0.5s forwards;
}
a:hover{
    text-decoration: none;
}